In recent years, with rapid development of display technologies, mobile products with biological identification functions have gradually become part of people's life. Particularly, increasing importance has been attached to fingerprinting for its identity uniqueness. Press type and slide type fingerprint identification based on a silicon substrate process has now been integrated into various mobile products. Moreover, future research will also focus on fingerprint identification technologies in a display region.
FIG. 1 illustrates a schematic structural view for an optical fingerprint identification device arranged in a display substrate. Specifically, each fingerprinting device 001 consists of two thin film transistors, one of them being a switching transistor 002 for controlling switches, and the other being a photosensitive transistor 003 serving as a photo sensor. During scanning of a fingerprint, due to differences between ridges and valleys of the fingerprint, light impinging on the finger will be reflected differently such that the light intensity reaching the photosensitive transistor 003 varies, resulting in different photocurrent differences. Under a control of the switching transistor 002, each current difference of the photosensitive transistor 003 is read out sequentially, and thereby detection for ridges and valleys of the fingerprint can be achieved.
In specific implementation, because of interference from ambient light and incident light, in the above optical fingerprint identification device, light received by the photosensitive transistor 003 after being reflected back carries lots of useless information. This influences detection for fingerprint detection signals and leads to a low signal-noise ratio for signals of such an optical fingerprint identification detection structure. Thus, the detection accuracy is limited.